<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body >
	<h1>这是左部</h1>
	<a href="main.html"  target="main" >第一个主菜单</a><br>
	<a href="main2.html" target="main" >第二个主菜单</a><br>
	<a href="main3.html" target="main" >第三个主菜单</a>
</body>
</html>